“Blade” computing systems have become popular recently due in part to the ability to house various primary components in slots in a relatively small enclosure. In addition, blade systems have the advantage of allowing customers to quickly and easily remove and install components to customize the system as the customer's needs change. The components install in slots in the enclosure and connect through a back-plane or mid-plane (hereinafter “connector plane”); thus, customization may be performed without removing, connecting or moving cables.
Through the use of switches, a “universal fabric” may be created in which, for the most part, a component in any slot is able to be coupled to and communicate with a component in any other slot as well as to externally connected components. Despite this benefit, in many systems it is necessary to separate data traffic between one set of components from data traffic between another set of components in order to prevent contamination of data. Zones may be created to establish such separation. For example, an IBM® BladeCenter®, may include processor or server blades, a pair of redundant switches, one or more integrated drive enclosure blades (I-DEBs) and an enclosure management module, as well as power supplies and cooling, within the same blade enclosure. The I-DEB includes a pair of redundant RAID controllers and a number of multiple disk drive trays (MDTs). Zoning keeps traffic between the server blades and the RAID controllers separate from traffic between RAID controller and the MDTs.
Additionally, each RAID controller in the I-DEB is coupled to the switch (via a connector plane) through to host adapter (HA) ports while the MDTs are coupled within the I-DEB to the RAID controllers through device adapter (DA) ports. This configuration permits both high availability (through the use of redundancy) and high performance (through the use of multiple ports). However, another form of DEB, a switched or non-integrated DEB (S-DEB) includes only MDTs and is managed by RAID controllers in an I-DEB but is coupled through DA ports. Consequently, with all ports of the I-DEB being used to exchange data with the server blade(s), the I-DEB has no unused ports with which to connect to an S-DEB installed in the blade enclosure without the use of cabling. And, in addition to increasing the complexity of the system and raising the risk of misconnections, cabling runs contrary to the philosophy and goals of a blade enclosure.
Consequently, it remains desirable for a blade system which is sufficiently flexible to be able to accommodate an I-DEB, with its integrated RAID controllers, and one or more S-DEBs, installed on the same internal connector plane and managed by the RAID controllers.